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The aim of the work was to resolve whether glutamine and arginine supplemented diets affect plasma and tissue (muscle, liver and intestinal mucosa) glutamine concentrations, as well as glutaminase and glutamine synthetase specific activities. The trial was performed in growing rats fed 10% protein diets for 3 weeks. Protein sources were: whey proteins (W); whey proteins+free glutamine (WG); whey proteins+arginine (WA); and casein+wheat protein hydrolysate+acid whey (39:39:22), as source containing protein-bound glutamine (CGW). Rats fed the control diet (6.4% glutamine) (W) showed comparable glutamine body stores to those of rats fed the WG diet. In fact, glutamine sup- plementation down-regulated the hepatic glutamine synthetic capacity of growing rats (W/WG: 6.8±0.3 vs 6.0±0.2 nmol/min/mg protein). Arginine supplementation of the diet (up to 9% of the protein content) resulted in a decrease in plasma and tissue glutamine concentrations (W/WA: plasma, 1218±51 vs 1031±48 μmol/L; liver 7.5±0.4 vs 6.5±0.2 μmol/g; muscle: 5.7±0.2 vs 4.0±0.2 μmol/g). These data suggest that glutamine supplementation of the diet does not increase plasma and tissue glutamine concentrations in healthy growing rats, while the addition of arginine to the diet decreases glutamine body stores.

In order to assess an endoscopic collection procedure, populations of bacteria in duodenal fluid from seven adult cats were compared in paired samples obtained by endoscopy and direct needle aspiration during laparotomy. Each sample of duodenal juice was subjected to quantitative and qualitative culture of bacteria under both aerobic and anaerobic conditions. There were no significant differences in total numbers or individual species of bacteria comparing the two collection procedures. These findings indicate that collection of duodenal juice by endoscopy using the procedure described provides a representative sample of small bowel fluid for the assessment of the bacterial flora. Therefore, there appears to be no need for more invasive or complicated sampling techniques when quantitative and qualitative culture of duodenal juice is indicated as part of an investigation of small bowel disease in cats.

Taurine kinetics in cats was investigated using a bolus dose of [15N]- and [1,2-13C2]taurine. The comparison of [15N]- and [13C2]taurine kinetics permitted an evaluation of the extent of taurine transamination. A methodology which involvesN-pentafluorobenzoyl di-n-butylamine derivatization of taurine and GC/MS measurements of the15N- and13C-enrichments in cat urine was developed. Accuracy of the measurements was determined using pure standard compounds and the results showed that [13C2]taurine does not interfere with [15N]taurine. In cats, no differences were observed between both tracers. Therefore, we conclude that taurine reversible transamination does not occur at a significant level in cats.